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392

CATS' EYES

made by Dr. Lindsay Johnson,1 who found that out of 180
Domestic Cats 111 had round pupils, and that in 19 the shape
was a pointed oval, intermediate conditions being offered by the
rest. These 180 comprised males and females of many varieties.
When the pupil of the Cat's eye contracts, it forms a vertical slit
with two pin holes, one at each end, through which alone light
appears to euter. In the Genet and the Civet the contraction
of the pupil is as in the Cat. In the Lion, Tiger—in fact
apparently in all the large Cats—the pupil retains its circular
shape even when contraction is fully effected. Dr. Johnson has,
furthermore/ made some interesting experiments upon the Seal's
eye—a creature which has, of course, to exert its powers of
vision in two media, and from one to the other. This is effected
by dilatation of the pupil when in the water, and its contraction
to a vertical slit with parallel margins and rounded ends when
in the air, the contraction being to some extent at least under
the influence of the animal's wilL
The coloration of these creatures is very varied: spots of
black, or bordered with black upon a more or less tawny ground-
colour, is the prevailing pattern. Stripes are also met with, as
in. the Tiger, but these are usually cross stripes,3 while in the
related "Viverridae there are many examples of longitudinal
stripes. Finally, many Cats, as for instance the Puma and the
Eyra, are " self-coloured "—have, that is to say, a uniform tint.
Just as the unstriped Horse sometimes shows traces of the
former existence of stripes, so the self-coloured Cats are occasion-
ally spotted when young; this is markedly so in the case of the
Puma; while the  lion  is spotted as a cub, and in the adult----
particularly in the lioness—there are distinct indications of these
spots. It is evident, therefore, that there are grounds for re-
garding a spotted condition to be antecedent, at least in some
cases, to a uniform colour. There are divers explanations of
these hues and of these changes. It is held by many that the
coloration has a relation to the habits of the creature: the
spotted Cats, it is pointed out, are largely arboreal; this is
eminently so with the Jaguar at any rate; and in an arboreal
1 "On the Pupils of the Felidae," Proc. ZooL Soc. 1894, p. 481.
s " OtHaervationa . .,- on the Seal's Eye," froc. Zool. Soe. 1893, p. 719.
* Ifc is noteworthy that in the Tiger some of the stripes have pale centres and
aa» thus like spots pulled out, while there are also small black spots.